A wireless communication system is a complex network of systems and elements. Typically elements include (1) a radio link to the mobile stations (e.g., cellular telephones), which is usually provided by at least one and typically several base stations, (2) communication links between the base stations, (3) a controller, typically one or more base station controllers or centralized base station controllers (BSC/CBSC), to control communication between and to manage the operation and interaction of the base stations, (4) a call controller (e.g., a mobile switching center (MSC)) or switch, typically a call agent (i.e., a “softswitch”), for routing calls within the system, and (5) a link to the land line or public switch telephone network (PSTN), which is usually also provided by the call agent.
Typically, a base station communicates with mobile stations via a forward link, which includes a forward paging channel (F-PCH). In particular, the paging channel may be used for transmission of messages such as paging messages associated with incoming calls (i.e., notification of incoming calls) and overhead messages (i.e., including control information) from the base station to the mobile stations. In a wireless communication system operating in accordance with a code division multiple access (CDMA) based communication protocol, for example, mobile stations are allocated a “slot” as to when to “listen” to the paging channel for messages. Typically, each mobile stations turns on a receiving unit (e.g., the mobile station “wakes up” from being idle) to monitor for a paging message and/or an overhead message from the base station during the slot, which occurs based on an operating slot cycle index (SCI). The operating SCI corresponds to an operating slot cycle, which is the period in which the slot reoccurs for the mobile station to monitor for transmission from the base station on the paging channel. That is, if there is no transmission from the base station, the receiving unit is turned off until the slot reoccurs according to the operating slot cycle. For example, the mobile station wakes up and monitors for transmission every 1.28, 2.56, 5.12, 10.24, 20.48, 40.96, 81.92 and 163.94 seconds with the SCI as a slot number from one of zero (0), one (1), two (2), three (3), four (4), five (5), six (6) and seven (7), respectively. The mobile station turns on the receiving unit (i.e., wakes up) more often to listen to the paging channel with a lower operating SCI. As a result, more power is conserved by the mobile station with a higher operating SCI.
The mobile station determines the operating SCI based on an internal SCI and a broadcasted SCI. In particular, the internal SCI may be pre-stored in the mobile station whereas the broadcasted SCI may be transmitted to the mobile station by the base station via the paging channel. Further, the broadcasted SCI may be determined by the base station based on the availability of communication resources. Typically, the mobile station uses the smaller of the internal SCI and the broadcasted SCI as the operating SCI. Thus, the base station controls how often a mobile station may “wake up” to monitor for transmission from the base station via the paging channel.
One aspect of designing a wireless communication system is to optimize the resources available to the wireless communication system. For example, a base station may provide a low broadcasted SCI (i.e., lower than the internal SCI) to assure short call setup times to give a mobile station more opportunities to receive a paging message associated with an incoming call and/or an overhead message including control information. Alternatively, the internal SCI may be set to a lower value than the broadcasted SCI such that the mobile station may use the internal SCI as the operating SCI at all times. In this case, the base station may lose control over call setup times for all mobile stations serviced by the base station. Nonetheless, a low value of either the internal SCI or the operating SCI (i.e., a short slot cycle) increases resource and power consumption by the mobile station. Longer slot cycles increase the capacity of the forward paging channel by reducing the frequency at which mobile stations access the forward paging channel and allow the mobile stations to conserve power. However, longer slot cycles may result in longer call setup times leading to customer dissatisfaction. That is, a short slot cycle may be desired in certain situations. For example, a user may wish for a shorter slot cycle in an emergency than during normal circumstances. In another example, emergency personnel such as police officers and firefighters may desire and/or need to select a shorter slot cycle when they are on duty as oppose to when they are off duty.
Therefore, a need exist for the mobile station to enable a preferred slot cycle to optimize communication resources of the wireless communication system and to conserve power of the mobile station.